At 01.11 hours and 01.14 hours on 24 Feb 1943, U-707 fired two torpedoes at stragglers just behind the convoy ON-166 during a squall and reported one ship sunk and another damaged. In fact, both torpedoes struck the Jonathan Sturges (Master Thorbjorn Leerberg) in the #1 and #2 holds. The engines were secured and the eight officers, 36 crewmen and 31 armed guards (the ship was armed with one 4in, one 3in and eight 20mm guns) abandoned ship in three lifeboats and four rafts, but one of the boats swamped in the heavy seas and the occupants were picked up by the other lifeboats. The vessel was last seen barely above the water with her stern in the air, almost broken in two forward of amidships. Four crew members and 11 armed guards went down with the ship.

On 27 February, a boat with 23 survivors came across a boat with three Lascar seamen from the Madoera, which had been torpedoed by U-653 (Feiler) at the same time. Four crew members and two armed guards were transferred to the foreign boat, which had already picked up eight crew members and four armed guards from rafts. The survivors in this boat were picked up by USS Belknap (DD 351) on 12 March and landed in Argentia, Newfoundland, two days later, but one crew member died of exposure. The other lifeboat with the master, the chief mate, 11 crew members and four armed guards was never heard of again, like another boat containing ten crew members and seven armed guards.

The last lifeboat with five crew members and two armed guards was found on 5 April by U-336 (Hunger) in 50°04N/25°15W, but one crew member already died of exposure on 22 March. The survivors were picked up by the U-boat and landed at Brest on 11 April, later transferred to a POW camp near Bremen.